1. Field of the Invention
The present invention generally relates to a temperature control method of controlling a temperature of a thermal fixing device provided in an image forming apparatus such as a copier, a printer, a facsimile machine, and a multi-function peripheral. More particularly, the present invention relates to a temperature control method of controlling a fixing device fixing the toner image onto a recording medium by heating a fixing member using a fixing heat source, contacting the heated fixing member with an imaging surface of the recording medium to melt a toner image formed on the image surface, a thermal fixing device employing the temperature control method, and an image forming apparatus including the thermal fixing device.
2. Description of the Related Art
In an image forming apparatus including a printer, a copier, a copier, a facsimile machine and the like, a fixing device has been widely used which fixes an image by heating and melting a toner image formed on a recording medium such as a sheet.
Generally, in such a fixing device for fixing an electrophotographic image formed as a toner image onto the recording medium, a fixing member such as a fixing belt is heated by supplying power to a heater as a fixing heat source, and the heat is used to heat and melt the toner image to be fixed onto the recording medium.
On the other hand, in such an image forming apparatus as described above, various types of recording media are used, including an ordinary sheet, a high-grade paper having a surface specially processed for letters, a resin sheet for an Over Head Projector (OHP) and the like.
Further, recently, the recording media used for image forming have various thicknesses and surface characteristics. Further, it is known that, in conventional fixing devices, the fixing characteristics and the image quality of the toner image formed on the recording media may vary depending on the types of the recording media.
Japanese Laid-open Patent Publication No. 08-137341 discloses an image forming apparatus employing a method of changing control information for forming an image depending on the information of the recording medium to be used, the information being input by user's input, so as to fix an appropriate image onto the recording medium based on the recording medium.
Further, Japanese Laid-open Patent Publication No. 2006-195422 discloses an image forming apparatus employing a method of changing a fixing condition by using recording medium information including surface characteristics, thickness, water content and the like so as to fix an image onto various types of recording media under appropriate fixing conditions.